In recent years, it has been proposed to use a cured product of a silicone resin composition as an encapsulating material for a semiconductor light-emitting element. However, a cured product of a silicone resin composition has a high gas permeability and a low barrier property against hydrogen sulfide gas in air. For this reason, there has been a problem in that, when encapsulating is made by using a cured product of a silicone resin composition, a silver film which is a back-surface reflection plate of the encapsulated semiconductor light-emitting element is corroded by hydrogen sulfide in air, thereby leading to decrease in the brightness of the semiconductor light-emitting element.
As a silicone resin composition that solves the aforementioned problem, there is proposed a curable silicone resin composition comprising a silicone resin in which the refractive index of the silicone resin composition after curing is 1.50 to 1.55 and a silicon oxide filler having an average particle size of 1 to 10 μm and being homogeneously dispersed at a concentration of 1 to 30 mass % in the silicone resin (See Patent Document 1.).